Polyacetals, preparation thereof and use thereof in detergents

ABSTRACT

Polyacetals useful as detergent additives contain units of the formula ##STR1## where R is hydrogen, C 1  -C 4  -alkyl or COOM, 
     M is C 1  -C 4  -alkyl or an alkali metal, ammonium or alkanolamine group, and 
     m is from 0 to 9, 
     have K values (determined by the method of H. Fikentscher on the sodium salt in 1% strength by weight aqueous solution at 25° C. and pH 7) of at least 8.5, and are prepared by polymerizing compounds of the formula ##STR2## where R is hydrogen, C 1  -C 4  -alkyl or COOM, 
     M is C 1  -C 4  -alkyl or an alkali metal, ammonium or alkanolamine group, 
     R 2  is C 1  -C 4  -alkyl, and 
     m is from 0 to 9, 
     in the presence of initiators and optionally comonomers with or without hydrolysis of the ester groups.

The present invention relates to polyacetals which as characteristicfeature contain copolymerized units of the formula ##STR3## where R ishydrogen, C₁ -C₄ -alkyl or COOM,

M is C₁ -C₄ -alkyl or an alkali metal, ammonium or alkanolamine group,and

m is from 0 to 9,

processes for preparing the polyacetals by polymerizing formyl esters inthe presence of initiators, and the use of the polyacetals as additivesin low-phosphate or phosphate-free detergents.

EP-B 0 001 004 discloses polymeric acetal carboxylates obtainable bypolymerizing glyoxylic esters in the presence of initiators. Thesepolymers contain as characteristic feature at least 4 units of theformula ##STR4## where M is an alkali metal, ammonium, C₁ -C₄ -alkyl oralkanolamine group.

These polymers are used as builders in detergents in amounts of at least1% by weight. The known polymeric acetal carboxylates hydrolyzerelatively rapidly in an acid medium to form components which arebiodegradable. However, the polymers are not easy to prepare, since themonomers, ie. the formyl esters, must first be prepared by heating thehemiacetal ester of glyoxylic acid in the presence of phosphoruspentoxide and purified. The esters are then polymerized using suitableinitiators, such as strong Lewis acids or the sodium salt of diethylmalonate. The resulting polymers are capped at the end groups withstructures which impart to the polymer the stability in alkaline mediarequired for use in detergents.

The polymerization of β-methoxycarbonylpropionaldehyde is known fromPolm. Sci, Polymer Chemistry Edition 17 (1979), 2999-3007, and fromMacromolecular Syntheses 7 (1979), 23-25.

It is an object of the present invention to provide novel detergentadditives.

We have found that this object is achieved by the use of polyacetalscontaining copolymerized units of formula ##STR5## where R is hydrogen,C₁ -C₄ -alkyl or COOM,

M is C₁ -C₄ -alkyl or an alkali metal, ammonium or alkanolamine group,and

m is from 0 to 9,

and optionally containing up to 50 mol % of at least one comonomerselected from the group consisting of the C₁ -C₁₀ -aldehydes, C₂ -C₄-alkylene oxides, epihalohydrins, epoxysuccinic acid and compounds ofthe formula ##STR6## where R' is C₁ -C₄ -alkyl, as copolymerized units,and having K values (determined by the method of H. Fikentscher on thesodium salt in 1% strength by weight aqueous solution at 25° C. and pH7) of at least 8.5, as additives in low-phosphate or phosphate-freedetergents in amounts of from 0.1 to 30% by weight, based on therespective formulations.

The compounds of the formula II are known. Formyl esters of the formulaII can be prepared for example by hydroformylation of monoethylenicallyunsaturated carboxylic esters with carbon monoxide and hydrogen atelevated temperatures and pressures; cf. for example J. Falbe, NewSyntheses with Carbon Monoxide, Springer Verlag 1980, or J. Wender andP. Pino, Organic Synthesis via Metal Carbonyls, J. Wiley & Sons, 1977.

Preferred polyacetals contain units of the formula I where

R is H or COOM,

m is 0 to 2, and

M is methyl, ethyl, sodium, potassium, or an ammonium or ethanolaminegroup.

The polyacetals may contain up to 50, preferably up to 30, mol % of atleast one comonomer selected from the group consisting of the C₁ -C₁₀-aldehydes, C₂ -C₄ -alkylene oxides, epihalohydrins, epoxysuccinic acidand compounds of the formula ##STR7## where R¹ is C₁ -C₄ -alkyl, ascopolymerized units. The polyacetals which contain copolymerized unitsof the formula I have K values (determined by the method of H.Fikentscher on the sodium salt in 1% strength by weight aqueous solutionat 25° C. and pH 7) of at least 8.5. Depending on the purity of themonomers which are used in the polymerization and the polymerizationconditions, the polyacetals obtained have K values of up to 200 orhigher. The number n of monomer units of the formula I in thepolyacetals is at least 4 and can be up to about 500, and is preferablywithin the range from 4 to 120.

The polyacetals are prepared by polymerizing compounds of the formula##STR8## where R² is preferably methyl or ethyl, R is preferablyhydrogen, and m is preferably 1-4,

with or without one or more of the abovementioned comonomers. Thepolymerization is carried out in the absence or presence of a solvent.Suitable solvents are for example halogenated hydrocarbons, such asdichloromethane and trichloroethane, aromatic hydrocarbons, such asbenzene, toluene, isopropylbenzene and xylene, ethers such as diethylether, dioxane and tetrahydrofuran or diethylene glycol dimethyl etherand also dimethylformamide and acetonitrile. The preferred solvents areethers, acetonitrile and dichloromethane. The solvents should becompletely or substantially anhydrous. Similarly, the monomers should beanhydrous. It is advisable to purify them by distillation before thepolymerization. The water content of the polymerizing mixture iscustomarily below 0.1% by weight. The polymerization is preferablycarried out under an inert gas atmosphere, for example under nitrogen,argon, helium or neon.

Suitable initiators are for example amines, such as triethylamine or the2-hydroxypyridine-H₂ O complex, strong Lewis acids, such as borontrifluoride or boron trifluoride etherates, antimony pentafluoride,phosphorus pentafluoride, phosphorus pentoxide, tin chloride, tinalkyls, titanium halides and titanium alkyls, trifluoroacetic acid,alkali metal alcoholates, butyllithium, Grignard compounds, potassiumcarbonate and also sodium diethyl malonate, sodium dimethyl malonate andsodium diethyl methylmalonate. The polymerization can also be carriedout in the presence of small amounts of hydroxyl and cyanide ions. Theinitiators are used in amounts of from 0.001 to 15 and preferably from0.01 to 10, % by weight. The preferred polymerization initiator forpreparing the polyacetals is phosphorous pentoxide.

To start the polymerization, the monomers, the initiator and, if used,the solvent are mixed. The substances can be mixed in any desired order,batchwise or continuously. The polymerization is customarily carried outwithin the temperature range from -100° to 50° C., preferably from -70°to +30° C. The most preferred temperature range for the polymerizationis from -20° to +30° C. Depending on the temperature and the initiator,the polymerization takes from some minutes to 8 days, preferably from 1hour to 4 days.

If the monomers are polymerized in a solvent, the concentration of themonomers therein is from 5 to 95, preferably from 15 to 90, % by weight.After the polymerization the solvent is distilled off and the polymer isisolated. Since formyl esters are used as monomers, the polymers containester groups which can be converted into salts by reaction with alkalimetal bases, ammonia or alkanolamines in an aqueous medium.

In the course of the polymerization in an organic solvent the growingpolyacetal chain reacts with solvent molecules, which are added to thechain as end groups and thus stabilize the polyacetal againstdegradation at alkaline pH. Such end groups can be for examplesubstituents which contain alkyl, alkenyl, phenyl, substituted phenyland oxygen, for example oxyalkyl groups, such as methoxy, ethoxy andalkylcarboxyl groups. Suitable end groups for stabilizing thepolyacetals are mentioned for example at length in EP-B-0 001 004 forother polyacetals. The particulars provided in said reference also applyto the polyacetals of the present invention. If the polymerization iscarried out with phosphorus pentoxide as initiator, the polyacetals thusobtainable have phosphate end groups.

The polyacetals which contain copolymerized units of the formula I areused as additives in low-phosphate or phosphate-free detergentformulations in amounts of 0.5 to 20% by weight, based on the detergentformulation. If the substituent M in the formula I is a C₁ -C₄ -alkylgroup, it is preferable to hydrolyze the ester groups of the polyacetalswith alkali metal bases, ammonia or alkanolamines before the polyacetalsare used as detergent additives. However, the polyacetals with estergroups can also be used directly in detergent formulations, since,during washing, the ester groups readily hydrolyze at an alkaline pH.However, the prior hydrolysis of the ester groups at up to 80° C.,preferably at up to 60° C., is preferable. The resulting polyacetals,which carry salts of carboxyl groups, act as builders in detergentformulations; low molecular weight products are good dispersants. Allthe polyacetals of the present invention are biodegradable.

The above-described polyacetals are used as additives in pulverulent andliquid detergents, preferably in phosphate-free or low-phosphatedetergents which contain not more than 25% by weight of sodiumtriphosphate. The polyacetals are used in amounts of from 0.1 to 30,preferably from 0.5 to 15, % by weight, based on the detergentformulation. The polyacetals to be used according to the presentinvention are good dispersants for clay in the washing liquor. Thisproperty is important because loamy soiling of textile material is verycommon. The polyacetals act as builders in detergent formulations,augment the detergency of the surfactants in detergents and also bringabout during the wash a reduction in the incrustation of the washedtextile material and make a significant contribution to the dispersal ofsoil in the washing liquor. Compared with known polymeric detergentadditives based on copolymers of acrylic and maleic acid as described inEP-B-0 025 551, the polyacetals to be used according to the presentinvention have the advantage that they are biodegradable to a highextent, for example to more than 90%. Compared with the copolymers ofmaleic acid and acrylic acid described as detergent additives in EP-B-0025 551, the polyacetals to be used according to the present inventionshow in particular improved compatibility in liquid detergentformulations.

The compositions of detergent formulations used for washing can differgreatly. The same is true of those used as cleaners. Both washing andcleaning detergent formulations customarily contain surfactants with orwithout builders. This is true not only of liquid but also ofpulverulent washing and cleaning detergent formulations. Examples of thecompositions of washing detergent formulations customary in Europe, theUSA and Japan may be found for example in table form in Chemical andEngineering News 67 (1989), 35.

The above-described polyacetals are used according to the invention indetergents which contain up to 45% by weight of phosphate, althoughtheir use in detergents having a reduced phosphate content (which is tobe understood as meaning a phosphate content of less than 25% by weightof sodium triphosphate) or in phosphate-free detergents is preferred.The polyacetals can be added to the detergent formulation in the form ofgranules, in the form of pastes, as a highly viscous mass, as adispersion or as a solution in a solvent. The polyacetals can also beadsorbed on the surface of diluents, for example sodium sulfate, orbuilders (zeolites or bentonites) and also on other solid constituentsof the detergent formulation.

The detergent formulations in question are pulverulent or liquid. Theycan differ in composition by region and according to the specificintended use.

Universal household detergents for drum type washing machines of thetype widely used in Europe usually contain from 5 to 10% by weight ofanionic surfactants, from 1 to 5% by weight of nonionic surfactants,from 1 to 5% by weight of foam regulators, such as silicone oils orsoaps, from 0 to 40% by weight of a water softener, such as sodiumcarbonate or pentasodium triphosphate, which may be replaced in whole orin part by the compounds of the present invention, from 0 to 30% byweight of an ion exchanger such as zeolite A, from 2 to 7% by weight ofsodium silicates as corrosion inhibitors, from 10 to 30% by weight ofbleaching agents, such as sodium perborate or sodium percarbonate,organic per-acids and salts thereof, from 0 to 5% by weight of bleachactivators, such as tetraacetylethylenediamine, pentaacetylglucose,hexaacetylsorbitol or acyloxybenzenesulfonate, stabilizers, such asmagnesium silicate or ethylenediaminetetraacetate, grayness inhibitors,such as carboxymethylcellulose, methylalkylcelluloses andhydroxyalkylcelluloses, vinyl acetate-grafted polyglycols, oligomericand polymeric terephthalic acid/ethylene glycol/polyethylene glycolesters, enzymes, fluorescent whitening agents, scents, fabric softeners,dyes, and diluents.

By contrast, the heavy duty detergents which are widely used in the USA,Japan and neighboring countries in tub type washing machines are usuallyfree of bleaching agents, but on the other hand their anionics contentis two to three times higher and they contain more wash alkalis, such assodium carbonate and sodium silicates (in general up to 25% by weight)and naturally they also lack the bleach activators and bleachstabilizers. The levels of surfactants and other ingredients can beappreciably higher in the case of detergent concentrates, which areavailable with little or no diluent. Detergents for delicate and coloredfabrics, wool detergents and hand washing detergents likewise usuallycontain no bleaching agents and only low levels of alkaline ingredientstogether with a correspondingly higher surfactant content.

Detergents for the commercial laundry sector are designed for thespecial conditions of industrial washing (soft water, continuouswashing) which make it possible to customize the detergent to the typeof article being washed and to the nature of the soil. Combinations aretherefore used in which one ingredient predominates or others arecompletely absent only to be added separately when required. For thisreason the surfactants, builders, alkalis and bleaching agents of thesedetergents vary within wide limits.

Suitable anionic surfactants for the aforementioned pulverulent washingdetergents, or washing powders, are for example sodiumalkylbenzenesulfonates, fatty alcohol sulfates and fatty alcoholpolyglycol ether sulfates. Individual compounds of this type are forexample C₈ -C₁₂ -alkylbenzenesulfonates, C₁₂ -C₁₈ -alkanesulfonates, C₁₂-C₁₆ -alkyl sulfates, C₁₂ -C₁₆ -alkyl sulfosuccinates and sulfatedethoxylated C₁₂ -C₁₆ -alkanols. Other suitable anionic surfactants aresulfated fatty acid alkanolamines, α-sulfo fatty acid esters, fatty acidmonoglycerides or reaction products of from 1 to 4 mol of ethylene oxidewith primary or secondary fatty alcohols or alkylphenols. Furthersuitable anionic surfactants are fatty acid esters and fatty acid amidesof hydroxy- or amino-carboxylic or -sulfonic acids, for example thefatty acid sarcosides, glycolates, lactates, taurides or isethionates.The anionic surfactants can be present in the form of the sodium,potassium and ammonium salts and also as soluble salts of organic bases,such as mono-, di- or triethanolamine or other substituted amines. Thegroup of anionic surfactants also includes the ordinary soaps, ie. thealkali metal salts of natural fatty acids.

Suitable nonionic surfactants (nonionics) are for example additionproducts of from 3 to 40, preferably from 4 to 20, mol of ethylene oxidewith 1 mol of fatty alcohol, alkylphenol, fatty acid, fatty amine, fattyacid amide or alkanesulfonamide. The abovementioned addition products ofethylene oxide may additionally contain up to 90% by weight, based oncocondensed ethylene oxide and propylene oxide, of propylene oxide ascocondensed units. The addition products which contain ethylene oxideand propylene oxide as cocondensed units may be modified byincorporation of butylene oxide as cocondensed units in amounts of up to60% by weight, based on the total alkylene oxide content. Of particularimportance are the addition products of from 5 to 16 mol of ethyleneoxide with coconut or tallow fatty alcohols, with oleyl alcohol or withsynthetic alcohols of from 8 to 18, preferably from 12 to 18, carbonatoms, and also with mono- or dialkylphenols having from 6 to 14 carbonatoms in the alkyl moieties. Besides these water-soluble nonionics,however, it is also possible to use water-insoluble or incompletelywater-soluble polyglycol ethers having from 1 to 4 ethylene glycol ethermoieties in the molecule, in particular if they are used together withwater-soluble nonionic or anionic surfactants.

Further usable nonionic surfactants are the water-soluble additionproducts of ethylene oxide with propylene glycol ethers,alkylenediaminopolypropylene glycol and alkylpolypropylene glycolshaving 1 to 10 carbon atoms in the alkyl chain that contain from 20 to250 ethylene glycol ether groups and from 10 to 100 propylene glycolether groups, the polypropylene glycol ether chain acting as hydrophobe.

It is also possible to use nonionic surfactants of the type of the amineoxides or sulfoxides.

The foaming power of the surfactants can be increased or reduced bycombining suitable surfactant types. A reduction can also be achieved byadding non-surfactant-like organic substances.

Further possible formulation ingredients of detergents includemonomeric, oligomeric and polymeric phosphonates, ether sulfonates basedon unsaturated fatty alcohols, eg. oleyl alcohol ethoxylate butyl etherand alkali metal salts thereof. These substances can be characterizedfor example with the aid of the formula RO(CH₂ CH₂ O)_(n) --C₄ H₈ --SO₃Na, where n is from 5 to 40 and R is oleyl.

The above-described polyacetals can also be used as additives in liquidwashing detergents. Liquid detergents contain liquid surfactants or elsesolid surfactants which are soluble or at least dispersible in thedetergent formulation. Suitable surfactants for this purpose are thoseproducts which are also used in pulverulent detergents but also liquidpolyalkylene oxides or polyalkoxylated compounds. If the polyacetals arenot directly miscible with the other constituents of the liquiddetergent, it is possible to prepare homogeneous mixtures with the aidof a small amount of a solubilizer, for example water or awater-miscible organic solvent, eg. isopropanol, methanol, ethanol,glycol, diethylene glycol or triethylene glycol or correspondingpropylene glycols. The amount of surfactant in liquid detergents iswithin the range from 4 to 50% by weight, based on the formulation as awhole, since in liquid detergents, too, the proportions of theingredients vary within wide limits according to regional marketconditions or the intended application.

Liquid detergents may contain water in amounts of from 10 to 60,preferably from 20 to 50, % by weight. However, they can also be free ofwater.

Water-free liquid detergents may also contain suspended or dispersedperoxo compounds for bleaching. Examples of suitable peroxo compoundsare sodium perborate, peroxocarboxylic acids and polymers having someperoxo-containing groups. Liquid detergents may also containhydrotropes. These are compounds such as 1,2-propanediol,cumenesulfonate and toluenesulfonate. If such compounds are used formodifying a liquid detergent, their amount is from 2 to 5% by weight,based on the total weight of the liquid detergent. In many cases anaddition of complexing agents has also proved advantageous for modifyingpulverulent and liquid detergents. Complexing agents are for exampleethylenediaminetetraacetic acid, nitrilotriacetate and isoserinediaceticacid and also phosphonates, such as aminotrismethylenephosphonic acid,hydroxyethanediphosphonic acid, ethylenediaminetetraethylenephosphonicacid and salts thereof. Complexing agents are used in amounts of 0 to10% by weight, based on the detergent. The detergents may also containcitrates, di- or triethanolamine, or opacifiers, fluorescent whiteningagents, enzymes, perfume oils and dyes. These substances, if they areused for modifying a liquid detergent, together account for up to 5% byweight. The detergents are preferably phosphate-free. However, they mayalso contain phosphates, for example pentasodium triphosphate and/ortetrapotassium pyrophosphate. If phosphates are used, they account forup to 45, preferably up to 25, % by weight of the total formulation ofthe detergent.

The polyacetals to be used according to the present invention can alsointeract with other known detergent additives (for example graynessinhibitors, clay dispersants and substances which augment the primarydetergency, color transfer inhibitors, bleach activators) in pulverulentand liquid detergents (phosphate-containing and phosphate-free) toproduce synergistic effects enhancing not only the dispersal ofparticulate soil but also the effectiveness of the other detergentadditive.

The percentages in the examples are by weight. The K values of thepolyacetals were determined by the method of H. Fikentscher,Cellulosechemie, 13 (1932), 58-64, 71-74, on the sodium salts of thepolyacetals in a 1% strength by weight aqueous solution at 25° C. and pH7.

EXAMPLES Example 1

A 100 ml capacity flask was charged with 50 ml of tetrahydrofuran and 2g (14.1 mmol) of phosphorus pentoxide under argon. 22.2 g (191.4 mmol)of methyl β-formylpropionate were added at 20° C. over 15 minutes, andthe reaction mixture was then stirred at 20° C. for 92 hours. Then thesolvent was removed under reduced pressure. The residue was a paleyellow porridge, to which 25% strength aqueous sodium hydroxide solutionwas gradually added with ice-cooling. The reaction mixture was then leftat pH 8-9 for 10 hours, and then concentrated, and the polymer wasprecipitated with ethanol. The poly-β-formylpropionic acid was obtainedin the form of the sodium salt as a white powder, which was dried underreduced pressure. The polymer had a K value of 18.7.

Example 2

The flask described in Example 1 was charged with 40 ml ofdichloromethane and 22.2 g (191.4 mmol) of methyl β-formylpropionate,and the contents were cooled down to -70° C. under argon. Then 0.3 g(2.1 mmol) of boron trifluoride etherate was added, and the reactionmixture was stirred at -70° C. for 4 hours. After the polymerization hadended, 2.3 g (28.9 mmol) of pyridine were added, the reaction mixturewas warmed to room temperature, and the solvent was distilled off underreduced pressure. This left a clear colorless product, which was cooleddown to 0° C. and gradually admixed with 25 g (156 mmol) of 25% strengthaqueous sodium hydroxide solution. The reaction mixture was left at 0°C. for 5 hours, then warmed to room temperature and left at thattemperature for a further 18 hours. A beige polymer salt is obtained onprecipitation in ethanol. The polymer had a K value of 10.7.

Example 3

The apparatus described in Example 1 was charged with 0.27 g (1.9 mmol)of phosphorus pentoxide and 50 ml of tetrahydrofuran under argon. 22.2 g(191.4 mmol) of methyl β-formylpropionate were then slowly added at 20°C., and the reaction mixture was stirred at 20° C. for 96 hours. Thesolvent was then distilled off under reduced pressure, 10 ml ofdichloromethane were added, followed by 3.7 ml of 2N aqueous sodiumhydroxide solution and 30 ml of saturated sodium bicarbonate solution,and the mixture was stirred for 15 minutes. The aqueous phase was thendecanted off, and the organic phase was washed twice with 30 ml ofsaturated aqueous sodium bicarbonate solution each time. The organicphase was then cooled down to 0° C., admixed with 25 ml of 10N aqueoussodium hydroxide solution, and stirred at room temperature for 2 hours.A pale yellow oil was obtained, to which 40 ml of ethanol were added,and the mixture was then stirred for 30 minutes. The polymer came downas a solid precipitate. The supernatant solution was decanted off, theprecipitate was dissolved, and the polymer was precipitated withmethanol. The poly-β-formylpropionic acid thus obtained in the form ofthe sodium salt was a beige powder and had a K value of 10.9.

Example 4

The apparatus specified in Example 1 was charged with 4.0 g (28.2 mmol)of phosphorus pentoxide and 50 ml of tetrahydrofuran under argon. 22.2 g(191.4 mmol) of methyl β-formylpropionate were then gradually added, andthe reaction mixture was stirred at 20° C. for 72 hours. The solvent wasthen distilled off under reduced pressure, and the residue was admixedwith 54.4 ml of 2N aqueous sodium hydroxide solution, 30 ml of saturatedsodium bicarbonate solution and 150 ml of water. The polymer wasfiltered off with suction and washed twice with 30 ml of saturatedaqueous sodium bicarbonate solution each time and then once with water.The polymer was then cooled down to 0° C. and saponified dropwise with25 ml of 10N aqueous sodium hydroxide solution at 25° C.Poly-β-formylpropionic acid was obtained in the form of the polysodiumsalt, which was precipitated with ethanol as a pale yellow powder of K15.3.

Example 5

The apparatus described in Example 1 was charged with 23.2 g (0.20 mol)of methyl β-formylpropionate and 4.5 ml of dichloromethane under argon,and the contents were cooled down to 0° C. 150 μl of a 0.05N solution ofsodium diethyl malonate in tetrahydrofuran was then added dropwise, andthe reaction mixture was stirred at 0° C. for 30 minutes. Thereafter thesame amount of sodium diethyl malonate in tetrahydrofuran was added(making a total of 0.015 mmol), and the mixture was stirred at 0° C. for20 hours. Then 4.6 g (60.5 mmol) of dimethoxymethane, 4.4 g (31 mmol) ofphosphorus pentoxide and then once more the same amount ofdimethoxymethane were added. The mixture was then stirred at 0° C. for20 hours and thereafter admixed with 60 ml of 2N sodium hydroxidesolution. The aqueous phase was decanted off, and the organic phase waswashed 3 times with 50 ml of saturated aqueous sodium bicarbonatesolution each time. The residue was admixed with 25 g of 25 % strengthaqueous sodium hydroxide solution, added dropwise, the temperaturerising to not more than 40° C., and the mixture stirred for 2 hours. 40ml of methanol were added, and the mixture was concentrated under anaspirator vacuum and then admixed with ethanol. This producedpoly-β-formylpropionic acid in the form of the polysodium salt as awhite powder of K 11.

Example 6

The apparatus described in Example 1 was charged with 2.0 g (14.1 mmol)of phosphorus pentoxide under argon and admixed with 50 ml oftetrahydrofuran by stirring. 22.72 g (195.9 mmol) of methylα-formylpropionate were then gradually added at room temperature, andthe reaction mixture was stirred at 20° C. for 72 hours. The solvent wasthen distilled off under reduced pressure, and 27 ml of 2N sodiumhydroxide solution were added to the residue. This mixture was stirredfor 15 minutes, then 50 ml of water were added, and the supernatantsolution was decanted off. The residue was washed with 100 ml ofsaturated aqueous sodium bicarbonate solution and then with 100 ml ofwater. It was then admixed with 20 ml of 10N sodium hydroxide solutionwith ice-cooling, and stirred at room temperature for 2 hours. Thepolymer was precipitated with 1:1 w/w ethanol/acetone and then dried.This produced poly-α-formylpropionic acid in the form of the polysodiumsalt having a K value of 14.2.

Example 7

The apparatus described in Example 1 was charged with 2.0 g (14.1 mmol)of phosphorus pentoxide and 50 ml of tetrahydrofuran under argon, slowlyfollowed by 24.74 g (142.2 mmol) of dimethyl formylsuccinate. Thereaction mixture was then stirred at room temperature for 120 hours.This produced a viscous oil, which was decanted off leaving a smallamount of white solid. The white solid was washed twice with 40 ml oftetrahydrofuran each time, and the wash liquors were combined with thedecanted oil. The solvent was then distilled off under reduced pressure,and the residue was cooled down to 0° C. Sufficient 25% strength aqueoussodium hydroxide solution was then added at that temperature until a pHof 8.5 had been obtained. Then 20 ml of water were added, and themixture was left to stand at 0° C. for 18 hours. The polymer wasprecipitated from a mixture of acetone and ethanol in a volume ratio of9:1. It had a K value of 12.4.

Comparative Example 1 (in accordance with Example 2 of U.S. Pat. No.4,224,420)

The apparatus described in Example 1 was charged with 8 ml of freshlydistilled dichloromethane and 16 ml (20.0 g, 0.22 mol) of methylglyoxylate, and the contents were cooled down to 0° C. At thattemperature 0.2 g of regenerated molecular sieve (3 Å) was added. Afterthe reaction had ended, the reaction mixture was warmed to roomtemperature. 7 ml of ethyl vinyl ether were added dropwise, and thesolution was then stirred overnight. 30 ml of toluene were added, themixture was stirred for 10 minutes, and the top phase was then decantedoff. The wash was repeated with 20 ml of toluene. This left a residue ofa white viscous product, which was admixed with 20 ml of 0.1N sodiumhydroxide solution and stirred for 20 minutes. The top phase was againdecanted off. Then 20 ml of 10M sodium hydroxide solution were addeddropwise, and the internal temperature rose to not more than 45° C. Thesaponification was carried out for 90 minutes, and the product wasprecipitated in methanol. The white powder obtained was dried underreduced pressure. It had a K value of 11.9.

Comparative Example 2 Sodium salt of monomeric β-formylpropionic acid

In the apparatus described in Example 1, 20 ml of the monomer methylβ-formylpropionate were cooled down to 0° C. and admixed dropwise with25% strength sodium hydroxide solution until a pH of from 8 to 9 hadbeen reached. The mixture was stirred at room temperature for a further15 h, and the sodium salt was then precipitated from ethanol and driedunder reduced pressure.

Example 8

The apparatus described in Example 1 was charged with 2.0 g (14.1 mmol)of phosphorus pentoxide and 50 ml of diethylene glycol dimethyl etherwere added. 20 ml (22.2 g, 191.4 mmol) of methyl β-formylpropionate wereadded dropwise over 15 minutes and the reaction mixture was left at roomtemperature for 96 h. It was then cooled down to 0° C. and graduallyadmixed with 30 g of 25% strength sodium hydroxide solution. After 6 hat room temperature the phases which had formed were separated, and thebottom phase was precipitated in ethanol. The product, which had a Kvalue of 9.4, was dried under reduced pressure.

Example 9

The apparatus described in Example 1 was charged with 0.81 g (5.7 mmol)of phosphorus pentoxide under argon, and 50 ml of dimethylglycol wereadded. 20 ml (22.2 g, 191.4 mmol) of methyl β-formylpropionate wereadded over 5 minutes, and the reaction mixture was stirred at roomtemperature for 94 h. After cooling down to 0° C., the reaction mixturewas admixed dropwise with 25 ml of 25% strength sodium hydroxidesolution and left at room temperature for 5 h. The resulting 2 phaseswere separated, the bottom phase was precipitated in 2:1methanol/acetone, and the precipitate was dried under reduced pressure.The product had a K value of 10.2.

Example 10

The apparatus described in Example 1 was charged with 0.27 g (1.9 mmol)of phosphorus pentoxide under argon, and 20 ml (22.2 g, 191.4 mmol) ofmethyl β-formylpropionate were then added with stirring. An exothermicreaction took place. The reaction mixture was left at room temperaturefor 90 h and then decanted off from the sediment, and the oily phase wasadmixed at 0° C. with 25 ml of 25% strength sodium hydroxide solution,added dropwise. After stirring at room temperature for 5 hours, theproduct was precipitated in 2:1 methanol/acetone. After filtration anddrying under reduced pressure the K value of the product was found to be9.0.

Example 11

The apparatus described in Example 1 was charged with 20 ml (22.2 g,191.4 mmol) of methyl β-formylpropionate under argon, and 3.3 μl oftriethylamine were added. The mixture was stirred at room temperaturefor 3 h and then at 50° C. for 47 h, at which point a further 3.3 μl oftriethylamine were added. The reaction temperature was raised to 90° C.and the mixture was left at that temperature for 27 h. It was thencooled down to 0° C., admixed dropwise with 50% strength sodiumhydroxide solution and subsequently stirred for 5 h. The product wasprecipitated in methanol, filtered off and dried under reduced pressure.The K value was 9.9.

Example 12

The apparatus described in Example 1 was charged with 2.0 g (14.1 mmol)of phosphorus pentoxide, and 50 ml of dimethylglycol were added. 20 ml(22.2 g, 191.4 mmol) of methyl β-formylpropionate were added dropwiseover 15 minutes, and the reaction mixture was left at room temperaturefor 96 h. It was cooled down to 0° C. and admixed dropwise with 30 g of25% strength sodium hydroxide solution, and then stirred at roomtemperature for 6 h. The phases were then separated, and the bottomphase was precipitated in ethanol. The product was dried under reducedpressure and was found to have a K value of 9.6.

Example 13

The apparatus described in Example 1 was charged with 2.0 g (14.1 mmol)of phosphorus pentoxide and 50 ml of tetrahydrofuran under argon, and 20ml ( 22.2 g, 191.4 mmol ) of methyl β-formylpropionate were added whilethe batch was cooled down to -70° C. It was then stirred at -70° C. for16 h and then warmed to 0° C., at which point 25 ml of 25% strengthsodium hydroxide solution were added dropwise. After stirring at roomtemperature for 5 hours, the tetrahydrofuran solvent was distilled offunder reduced pressure, and the product was precipitated in methanol.After filtration, the product was dried under reduced pressure. Thewhite powder had a K value of 10.9.

Example 14

The apparatus described in Example 1 was charged with 2.0 g (14.1 mmol)of phosphorus pentoxide and 50 ml of dioxane, and 20 ml (22.2 g, 191.4mmol) of methyl β-formylpropionate were added. Following a reaction timeof 72 h at room temperature, 25 ml of 25% strength sodium hydroxidesolution were added dropwise. The resulting 2 phases were separated, andthe bottom phase was precipitated in 2:1 methanol/acetone. The productwas dried under reduced pressure and was found to have a K value of 9.5.

Example 15

The apparatus described in Example 1 was charged with 2.0 g (14.1 mmol)of phosphorus pentoxide and 50 ml of toluene, and 20 ml (22.2 g, 191.4mmol) of methyl β-formylpropionate were added. Following a reaction timeof 72 h at room temperature, 25 ml of 25% strength sodium hydroxidesolution were added dropwise. The resulting 2 phases were separated, andthe bottom phase was precipitated in 2:1 methanol/acetone. The productwas dried under reduced pressure and was found to have a K value of 9.4.

APPLICATION EXAMPLES

Clay Dispersion

The removal of particulate soil from fabric surfaces is augmented by thepresence of polyelectrolytes. Stabilizing the dispersion which forms asthe particles are detached from the fabric surface is an importantfunction of these polyelectrolytes. The stabilizing effect of theanionic dispersants is due to the fact that, as a consequence of theadsorption of dispersant molecules on the surfaces of the solids, thesurface charge thereof and hence the repulsion increases. Furtherfactors having a bearing on the stability of a dispersion include stericeffects, the temperature, the pH and the electrolyte concentration.

The clay dispersion (CD) test described hereinafter can be used toassess the dispersing power of various polyelectrolytes in a simplemanner.

CD Test

Particulate soil is represented by finely ground china clay SPS 151.1 gof clay is intensively dispersed in 98 ml of water in a 100 ml cylinderin the presence of 1 ml of a 0.1% strength sodium salt solution of thepolyelectrolyte for 10 minutes. Immediately after the stirring has beenstopped, a sample of 2.5 ml is removed from the center of the cylinderand diluted to 25 ml and the turbidity measured in a turbidimeter. Afterthe dispersion has stood for 30 and 60 minutes, further samples aretaken and again measured in the turbidimeter. The turbidity of thedispersion is reported in nephelometric turbidity units (NTUs). The lessthe dispersion settles on storage, the higher the measured turbidityvalues are and the stabler the dispersion is. The second physicalparameter determined is the dispersion constant τ, which describes thetime course of the sedimentation process. Since the sedimentationprocess approximates to a monoexponential time law, τ indicates the timewithin which the turbidity decreases to 1/e-th of the original level attime t=0.

The higher value of τ, the slower the rate of sedimentation in thedispersion.

The CD test was carried out for the sodium salts of the polymersobtained as described in Examples 8 to 15. The results are indicatedbelow in the table together with the results of the comparativeexamples.

    ______________________________________                                               Reaction pro-            Dis-                                                 duct obtained                                                                          Turbidity after persion                                              as described                                                                           storage [NTU]   constant                                             in       at once 30 min  60 min                                                                              τ [min]                             ______________________________________                                        Example  Example                                                              16        8         680     600   530   240.7                                 17        9         680     630   570   346.9                                 18       10         730     640   600   341.4                                 19       11         700     630   550   253.7                                 20       12         690     620   580   362.7                                 21       13         740     610   540   197.4                                 22       14         740     620   580   300.7                                 23       15         750     640   600   319.3                                 Comparative                                                                            Comparative                                                          Example  Example                                                              1        1          570     470   400   169.8                                 2        2          630      40    35    36.2                                 3        --         600      37    33    41.4                                 ______________________________________                                    

The measurements reveal that the polyacetals to be used according to thepresent invention give dispersions which, after standing for 60 minutes,have distinctly higher turbidity values than the reported comparisons.Together with the distinctly higher dispersion constants this means thatthe polyacetals to be used according to the present invention are betterable to disperse clay and at the same time make it possible to preparedispersions having a longer storage life. Applied to washing processes,this means an improvement in the primary detergency (better soilremoval) and at the same time, due to formation of stable dispersions, areduced danger of the soil present in the washing liquor from the firstpart of the operation being redeposited on the washed fabric.

We claim:
 1. A detergent comprising surfactants and other conventionaladditives, which contains, 0,1 to 30% by weight of a polyacetal whichcontains copolymerized units of the formula ##STR9## where R ishydrogen, C₁ -C₄ -alkyl or COOM,M is C₁ -C₄ -alkyl or an alkali metal,ammonium or alkanolamine group, and m is from 0 to 9,and has a K value(determined by the method of H. Fikentscher on the sodium salt in 1%strength by weight aqueous solution at 25° C. and pH 7) of at least 8.5.2. A detergent as claimed in claim 1, wherein the polyacetal containscopolymerized units of the formula I, whereinR is H or COOM, m is 0 to 2and M is methyl, ethyl, sodium, potassium, or an ammonium orethanolammonium group.
 3. A detergent as claimed in claim 1, wherein thepolyacetal is methyl β-formylpropionate.
 4. A detergent as claimed inclaim 1, wherein the polyacetal is dimethyl formylsuccinate.
 5. Adetergent as claimed in claim 1, wherein the polyacetal contains, ascopolymerized units, up to 50 mol.-% of at least one comonomer selectedfrom the group consisting of C₁ -C₁₀ -aldehydes, C₂ -C₄ -alkyleneoxides, epihalohydrins, epoxysuccinic acid and compounds of the formula##STR10## where R¹ is C₁ -C₄ -alkyl.